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binutils-gdb/gdb/cli/cli-decode.h
Pedro Alves 9d0faba9f5 Introduce generic command options framework 
This commit adds a generic command options framework, that makes it
easy enough to add '-'-style options to commands in a uniform way,
instead of each command implementing option parsing in its own way.

Options are defined in arrays of option_def objects (for option
definition), and the same options definitions are used for supporting
TAB completion, and also for generating the relevant help fragment of
the "help" command.  See the gdb::options::build_help function, which
returns a string with the result of replacing %OPTIONS% in a template
string with an auto-generated "help" string fragment for all the
passed-in options.

Since most options in GDB are in the form of "-OPT", with a single
dash, this is the format that the framework supports.

I like to think of gdb's "-OPT" as the equivalent to getopt's long
options format ("--OPT"), and gdb's "/" as the equivalent to getopt's
short options format.  getopt's short options format allows mixing
several one-character options, like "ls -als", kind of similar to
gdb's "x /FMT" and "disassemble /MOD", etc.  While with gdb's "-"
options, the option is expected to have a full name, and to be
abbreviatable.  E.g., "watch -location", "break -function main", etc.

This patch only deals with "-" options.  The above comment serves more
to disclose why I don't think we should support mixing several
unrelated options in a single "-" option invocation, like "thread
apply -qcs" instead of "thread apply -q -c -s".

The following patches will add uses of the infrastructure to several
key commands.  Most notably, "print", "compile print", "backtrace",
"frame apply" and "thread apply".  I tried to add options to several
commands in order to make sure the framework didn't leave that many
open holes open.

Options use the same type as set commands -- enum var_types.  So
boolean options are var_boolean, enum options are var_enum, etc.  The
idea is to share code between settings commands and command options.
The "print" options will be based on the "set print" commands, and
their names will be the same.  Actually, their definitions will be the
same too.  There is a function to create "set/show" commands from an
array for option definitions:

 /* Install set/show commands for options defined in OPTIONS.  DATA is
    a pointer to the structure that holds the data associated with the
    OPTIONS array.  */
 extern void add_setshow_cmds_for_options (command_class cmd_class, void *data,
					   gdb::array_view<const option_def> options,
					   struct cmd_list_element **set_list,
					   struct cmd_list_element **show_list);

That will be used by several following patches.

Other features:

 - You can use the "--" delimiter to explicitly indicate end of
   options.  Several existing commands use this token sequence for
   this effect already, so this just standardizes it.

 - You can shorten option names, as long as unambiguous.  Currently,
   some commands allow this (e.g., break -function), while others do
   not (thread apply all -ascending).  As GDB allows abbreviating
   command names and other things, it feels more GDB-ish to allow
   abbreviating option names too, to me.

 - For boolean options, 0/1 stands for off/on, just like with boolean
   "set" commands.

 - For boolean options, "true" is implied, just like with boolean "set
   commands.

These are the option types supported, with a few examples:

 - boolean options (var_boolean).  The option's argument is optional.

   (gdb) print -pretty on -- *obj
   (gdb) print -pretty off -- *obj
   (gdb) print -p -- *obj
   (gdb) print -p 0 -- *obj

 - flag options (like var_boolean, but no option argument (on/off))

   (gdb) thread apply all -s COMMAND

 - enum options  (var_enum)

   (gdb) bt -entry-values compact
   (gdb) bt -e c

 - uinteger options (var_uinteger)

   (gdb) print -elements 100 -- *obj
   (gdb) print -e 100 -- *obj
   (gdb) print -elements unlimited -- *obj
   (gdb) print -e u -- *obj

 - zuinteger-unlimited options (var_zuinteger_unlimited)

   (gdb) print -max-depth 100 -- obj
   (gdb) print -max-depth -1 -- obj
   (gdb) print -max-depth unlimited -- obj

Other var_types could be supported, of course.  These were just the
types that I needed for the commands that I ported over, in the
following patches.

It was interesting (and unfortunate) to find that we need at least 3
different modes to cover the existing commands:

- Commands that require ending options with "--" if you specify any
  option: "print" and "compile print".

- Commands that do not want to require "--", and want to error out if
  you specify an unknown option (i.e., an unknown argument that starts
  with '-'): "compile code" / "compile file".

- Commands that do not want to require "--", and want to process
  unknown options themselves: "bt", because of "bt -COUNT",
  "thread/frame apply", because "-" is a valid command.

The different behavior is encoded in the process_options_mode enum,
passed to process_options/complete_options.

For testing, this patch adds one representative maintenance command
for each of the process_options_mode values, that are used by the
testsuite to exercise the options framework:

 (gdb) maint test-options require-delimiter
 (gdb) maint test-options unknown-is-error
 (gdb) maint test-options unknown-is-operand

and adds another command to help with TAB-completion testing:

 (gdb) maint show test-options-completion-result

See their description at the top of the maint-test-options.c file.

Docs/NEWS are in a patch later in the series.

gdb/ChangeLog:
2019-06-13  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SUBDIR_CLI_SRCS): Add cli/cli-option.c.
	(COMMON_SFILES): Add maint-test-settings.c.
	* cli/cli-decode.c (boolean_enums): New global, factored out from
	...
	(add_setshow_boolean_cmd): ... here.
	* cli/cli-decode.h (boolean_enums): Declare.
	* cli/cli-option.c: New file.
	* cli/cli-option.h: New file.
	* cli/cli-setshow.c (parse_cli_boolean_value(const char **)): New,
	factored out from ...
	(parse_cli_boolean_value(const char *)): ... this.
	(is_unlimited_literal): Change parameter type to pointer to
	pointer.  Adjust and advance ARG pointer.
	(parse_cli_var_uinteger, parse_cli_var_zuinteger_unlimited)
	(parse_cli_var_enum): New, factored out from ...
	(do_set_command): ... this.  Adjust.
	* cli/cli-setshow.h (parse_cli_boolean_value)
	(parse_cli_var_uinteger, parse_cli_var_zuinteger_unlimited)
	(parse_cli_var_enum): Declare.
	* cli/cli-utils.c: Include "cli/cli-option.h".
	(get_ulongest): New.
	* cli/cli-utils.h (get_ulongest): Declare.
	(check_for_argument): New overloads.
	* maint-test-options.c: New file.

gdb/testsuite/ChangeLog:
2019-06-13  Pedro Alves  <palves@redhat.com>

	* gdb.base/options.c: New file.
	* gdb.base/options.exp: New file.
2019-06-13 00:18:12 +01:00

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/* Header file for GDB command decoding library.
Copyright (C) 2000-2019 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef CLI_CLI_DECODE_H
#define CLI_CLI_DECODE_H
/* This file defines the private interfaces for any code implementing
command internals. */
/* Include the public interfaces. */
#include "command.h"
#include "gdb_regex.h"
#include "cli-script.h"
#if 0
/* FIXME: cagney/2002-03-17: Once cmd_type() has been removed, ``enum
cmd_types'' can be moved from "command.h" to "cli-decode.h". */
/* Not a set/show command. Note that some commands which begin with
"set" or "show" might be in this category, if their syntax does
not fall into one of the following categories. */
typedef enum cmd_types
{
not_set_cmd,
set_cmd,
show_cmd
}
cmd_types;
#endif
/* This structure records one command'd definition. */
struct cmd_list_element
{
cmd_list_element (const char *name_, enum command_class theclass_,
const char *doc_)
: name (name_),
theclass (theclass_),
cmd_deprecated (0),
deprecated_warn_user (0),
malloced_replacement (0),
doc_allocated (0),
hook_in (0),
allow_unknown (0),
abbrev_flag (0),
type (not_set_cmd),
var_type (var_boolean),
doc (doc_)
{
memset (&function, 0, sizeof (function));
}
~cmd_list_element ()
{
if (doc && doc_allocated)
xfree ((char *) doc);
}
DISABLE_COPY_AND_ASSIGN (cmd_list_element);
/* Points to next command in this list. */
struct cmd_list_element *next = nullptr;
/* Name of this command. */
const char *name;
/* Command class; class values are chosen by application program. */
enum command_class theclass;
/* When 1 indicated that this command is deprecated. It may be
removed from gdb's command set in the future. */
unsigned int cmd_deprecated : 1;
/* The user needs to be warned that this is a deprecated command.
The user should only be warned the first time a command is
used. */
unsigned int deprecated_warn_user : 1;
/* When functions are deprecated at compile time (this is the way
it should, in general, be done) the memory containing the
replacement string is statically allocated. In some cases it
makes sense to deprecate commands at runtime (the testsuite is
one example). In this case the memory for replacement is
malloc'ed. When a command is undeprecated or re-deprecated at
runtime we don't want to risk calling free on statically
allocated memory, so we check this flag. */
unsigned int malloced_replacement : 1;
/* Set if the doc field should be xfree'd. */
unsigned int doc_allocated : 1;
/* Flag that specifies if this command is already running its hook. */
/* Prevents the possibility of hook recursion. */
unsigned int hook_in : 1;
/* For prefix commands only:
nonzero means do not get an error if subcommand is not
recognized; call the prefix's own function in that case. */
unsigned int allow_unknown : 1;
/* Nonzero says this is an abbreviation, and should not
be mentioned in lists of commands.
This allows "br<tab>" to complete to "break", which it
otherwise wouldn't. */
unsigned int abbrev_flag : 1;
/* Type of "set" or "show" command (or SET_NOT_SET if not "set"
or "show"). */
ENUM_BITFIELD (cmd_types) type : 2;
/* What kind of variable is *VAR? */
ENUM_BITFIELD (var_types) var_type : 4;
/* Function definition of this command. NULL for command class
names and for help topics that are not really commands. NOTE:
cagney/2002-02-02: This function signature is evolving. For
the moment suggest sticking with either set_cmd_cfunc() or
set_cmd_sfunc(). */
void (*func) (struct cmd_list_element *c, const char *args, int from_tty)
= nullptr;
/* The command's real callback. At present func() bounces through
to one of the below. */
union
{
/* If type is not_set_cmd, call it like this: */
cmd_const_cfunc_ftype *const_cfunc;
/* If type is set_cmd or show_cmd, first set the variables,
and then call this: */
cmd_const_sfunc_ftype *sfunc;
}
function;
/* Local state (context) for this command. This can be anything. */
void *context = nullptr;
/* Documentation of this command (or help topic).
First line is brief documentation; remaining lines form, with it,
the full documentation. First line should end with a period.
Entire string should also end with a period, not a newline. */
const char *doc;
/* For set/show commands. A method for printing the output to the
specified stream. */
show_value_ftype *show_value_func = nullptr;
/* If this command is deprecated, this is the replacement name. */
const char *replacement = nullptr;
/* If this command represents a show command, then this function
is called before the variable's value is examined. */
void (*pre_show_hook) (struct cmd_list_element *c) = nullptr;
/* Hook for another command to be executed before this command. */
struct cmd_list_element *hook_pre = nullptr;
/* Hook for another command to be executed after this command. */
struct cmd_list_element *hook_post = nullptr;
/* Nonzero identifies a prefix command. For them, the address
of the variable containing the list of subcommands. */
struct cmd_list_element **prefixlist = nullptr;
/* For prefix commands only:
String containing prefix commands to get here: this one
plus any others needed to get to it. Should end in a space.
It is used before the word "command" in describing the
commands reached through this prefix. */
const char *prefixname = nullptr;
/* The prefix command of this command. */
struct cmd_list_element *prefix = nullptr;
/* Completion routine for this command. */
completer_ftype *completer = symbol_completer;
/* Handle the word break characters for this completer. Usually
this function need not be defined, but for some types of
completers (e.g., Python completers declared as methods inside
a class) the word break chars may need to be redefined
depending on the completer type (e.g., for filename
completers). */
completer_handle_brkchars_ftype *completer_handle_brkchars = nullptr;
/* Destruction routine for this command. If non-NULL, this is
called when this command instance is destroyed. This may be
used to finalize the CONTEXT field, if needed. */
void (*destroyer) (struct cmd_list_element *self, void *context) = nullptr;
/* Pointer to variable affected by "set" and "show". Doesn't
matter if type is not_set. */
void *var = nullptr;
/* Pointer to NULL terminated list of enumerated values (like
argv). */
const char *const *enums = nullptr;
/* Pointer to command strings of user-defined commands */
counted_command_line user_commands;
/* Pointer to command that is hooked by this one, (by hook_pre)
so the hook can be removed when this one is deleted. */
struct cmd_list_element *hookee_pre = nullptr;
/* Pointer to command that is hooked by this one, (by hook_post)
so the hook can be removed when this one is deleted. */
struct cmd_list_element *hookee_post = nullptr;
/* Pointer to command that is aliased by this one, so the
aliased command can be located in case it has been hooked. */
struct cmd_list_element *cmd_pointer = nullptr;
/* Start of a linked list of all aliases of this command. */
struct cmd_list_element *aliases = nullptr;
/* Link pointer for aliases on an alias list. */
struct cmd_list_element *alias_chain = nullptr;
/* If non-null, the pointer to a field in 'struct
cli_suppress_notification', which will be set to true in cmd_func
when this command is being executed. It will be set back to false
when the command has been executed. */
int *suppress_notification = nullptr;
};
extern void help_cmd_list (struct cmd_list_element *, enum command_class,
const char *, int, struct ui_file *);
/* Functions that implement commands about CLI commands. */
extern void help_cmd (const char *, struct ui_file *);
extern void apropos_cmd (struct ui_file *, struct cmd_list_element *,
bool verbose, compiled_regex &, const char *);
/* Used to mark commands that don't do anything. If we just leave the
function field NULL, the command is interpreted as a help topic, or
as a class of commands. */
extern void not_just_help_class_command (const char *arg, int from_tty);
/* Exported to cli/cli-setshow.c */
extern void print_doc_line (struct ui_file *, const char *);
/* The enums of boolean commands. */
extern const char * const boolean_enums[];
/* The enums of auto-boolean commands. */
extern const char * const auto_boolean_enums[];
/* Verify whether a given cmd_list_element is a user-defined command.
Return 1 if it is user-defined. Return 0 otherwise. */
extern int cli_user_command_p (struct cmd_list_element *);
extern int find_command_name_length (const char *);
#endif /* CLI_CLI_DECODE_H */
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